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Obstetric and Gynecological Nursing - The Carter Center

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penetrate. Viruses, however, can cross freely <strong>and</strong> may cause<br />

congenital abnormalities as in the case the rubella virus <strong>and</strong><br />

HIV virus.<br />

Endocrine - Human chorinnic gondotroghin (HCG) is<br />

produced by the cytotrophoblastic layer of the chorinonic villi.<br />

• Oestrogens as the activity of the corpus luteum declines,<br />

the placenta takes over the production of oestrogen,<br />

which are secreted in large amounts through out<br />

pregnancy.<br />

• Human placental lactogen (HpL) has a role in glucose<br />

metabolism in pregnancy.<br />

• Progestrone<br />

3.4. <strong>The</strong> Fetal Circulation<br />

At the birth there is a dramatic alteration in this situation <strong>and</strong><br />

almost instaneous change must occur. Besides this all, the<br />

postnatal structures must be in place <strong>and</strong> ready to take over.<br />

<strong>The</strong>re are several temporary structures inaddition to the<br />

placenta itself <strong>and</strong> the umblical cord <strong>and</strong> these enable the<br />

fetal circulation to take place while allowing for the changes at<br />

birth.<br />

<strong>The</strong> Umbilical vein Leads from the umblical cord to the<br />

underside of the liver <strong>and</strong> carries blood rich in oxygen <strong>and</strong><br />

41

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